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Participant metehanaltunlu
Participant
6,357 Views
Registered: ‎05-04-2010

Changing oscillator on Spartan-3E starter kit...

Hello,

 

As you know, there exists a 50MHz. oscillator on Spartan-3E starter kit.

 

Is it possible to change it to 100 MHz.? or what is the range of frequencies that we can use  for the oscillator on Spartan-3E starter kit?

 

I can see that the same oscillator is connected to on board CPLD that does some memory configuration work. I wonder if  changing this oscillator effects the operation of CPLD and/or the other components on the board.

 

Do you have any idea?

 

Thank you

metehan

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6 Replies
Instructor
Instructor
6,343 Views
Registered: ‎08-14-2007

Re: Changing oscillator on Spartan-3E starter kit...

If you only need the 100 MHz inside the Spartan 3E FPGA, it is much better to

just use a DCM to boost the frequency instead of changing the oscillator.

-- Gabor
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Participant metehanaltunlu
Participant
6,315 Views
Registered: ‎05-04-2010

Re: Changing oscillator on Spartan-3E starter kit...

Thank you for the answer,

 

Yes i know and used DCMs to generate different clocks. But ,as you know, DCMs add jitter on the clock, so for the applications that require very low jitter, i want to know if i can change the crystal oscillator to 100MHz. (or otrher higher frequencies) and whether this change effect the operation of on board CPLD?

 

Mete

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Historian
Historian
6,297 Views
Registered: ‎02-25-2008

Re: Changing oscillator on Spartan-3E starter kit...

 


@metehanaltunlu wrote:

Thank you for the answer,

 

Yes i know and used DCMs to generate different clocks. But ,as you know, DCMs add jitter on the clock, so for the applications that require very low jitter, i want to know if i can change the crystal oscillator to 100MHz. (or otrher higher frequencies) and whether this change effect the operation of on board CPLD?

 

Mete


 

Sure you can change the oscillator, if you're handy with SMT rework.

As to whether it affects anything else -- look at the schematic and see if that oscillator goes anywhere other than the FPGA.

----------------------------Yes, I do this for a living.
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Participant metehanaltunlu
Participant
6,286 Views
Registered: ‎05-04-2010

Re: Changing oscillator on Spartan-3E starter kit...

Yes, as i said before, the same oscillator goes to on board CPLD that does some memory configuration work for FPGA. Do you think changing oscillator makes on board CPLD work incorrectly in terms of memory configuration work?

 

And if it doesn't effect CPLD, what is the range that i can change the oscillator frequency?

 

Mete

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Instructor
Instructor
6,279 Views
Registered: ‎08-14-2007

Re: Changing oscillator on Spartan-3E starter kit...

Unless I looked at the wrong schematic, I thought that kit had at least two oscillator

sockets, so you shouldn't need to change the existing oscillator, just add another one.

-- Gabor
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Highlighted
Observer scrts
Observer
6,062 Views
Registered: ‎06-22-2009

Re: Changing oscillator on Spartan-3E starter kit...

True, added mine like this: 100MHz clock